Thread friction is conventionally measured by hauling a thread over a cylindrical surface and measuring the tension in the thread either side of the surface. If T.sub.1 is the input tension, T.sub.2 is the output tension and 0 is the angle the thread turns around the cylindrical surface, the coefficient of friction .mu. is calculated from the relationship EQU T.sub.2 /T.sub.1 =e.mu..sup.74
which gives .mu.=(log T.sub.2 -log T.sub.1)/.theta.
Conventional methods for measuring thread tension involve running the thread in a thread path including a roller displaceable against a resilient bias and measuring the displacement of the roller. Using such tension measuring arrangements for friction measurement results in a complicated arrangement and this complication is reflected in the cost of equipment commercially available for measuring thread frictional coefficients.
The present invention provides a simpler and therefore more reliable and less expensive thread friction measuring arrangement.